Method for sending preamble sequence and user equipment

ABSTRACT

The present invention discloses a method for sending a preamble sequence and user equipment. The method includes: determining a transmit power for sending a preamble sequence, where the transmit power meets the following formula: Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER i   preamble   _   transmission   _   counter +PL}, where Power is the determined transmit power, Pmax is a maximum transmit power of user equipment, PL is obtained by estimating according to a downlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER i   preamble   _   transmission   _   counter  is a target receive power of the preamble sequence, where PREAMBLE_RECEIVED_TARGET_POWER i   preamble   _   transmission   _   counter =preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X i +(preamble_transmission_counter−1)*powerRampingStep; and preambleInitialReceivedTargetPower is an initial target receive power of the preamble sequence, DELTA_PREAMBLE is a power offset based on a format of the preamble sequence, powerRampingStep is a power ramp step, preamble_transmission_counter is a repetition count for transmitting the preamble sequence, and X i  is a power offset corresponding to a preamble sequence resource pool i for coverage enhancement random access; and sending the preamble sequence according to the determined transmit power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2013/081411, filed on Aug. 13, 2013, which is hereby incorporatedby reference in its entirety.

TECHNICAL FIELD

The present invention relates to the field of communicationstechnologies, and in particular, to a method for sending a preamblesequence and user equipment.

BACKGROUND

The Internet of Things is referred to as machine to machine (Machine toMachine, M2M) for short, and was first proposed in 1999. A definition isrelatively simple: All objects are connected to the Internet by usinginformation sensing devices, so as to implement smart identification andmanagement. The objects are combined with the Internet, which canimplement remote perception and control of all the objects; therefore, asmarter production and living system is generated. The Internet ofThings is larger than the existing Internet, and is widely applied tomultiple fields, such as a smart grid, intelligent transportation,environment protection, government work, public security, smart homefurnishing, intelligent firefighting, industrial monitoring, elderlycaring, and personal health.

The standardization organization 3rd generation partnership project(3GPP) dedicatedly founded a project team that studies enhancements andoptimization that need to be made to a mobile communication networkbecause of introduction of an machine type communication (MTC) device.Vodafone (Vodafone) proposes that, many M2M devices, such as an electricmeter, may be placed at a location in which coverage is relatively poor,such as a basement, and these devices may need a coverage enhancementamount of 20 dB to meet a requirement. Even if user equipment sends asequence always by using a maximum transmit power, a power received by atarget base station still cannot reach a target receive power, and evenis far lower than the target receive power. In this case, the userequipment may transmit a sequence at multiple transmission timeintervals (TTI, Transmission Time interval), or transmit a sequence inmultiple subframes (subframe), so as to achieve an effect of repeatedsending. On a base station side, these sequences are collected andcombined, so as to achieve an objective of improving a receive signal tonoise ratio. For example:

Quantity of transmission time intervals Coverage enhancement amount(#TTI) (dB) 1 0 (reference for comparison) 2 3 4 5

There is a correspondence between a repetition count, that is, aquantity of occupied transmission time intervals, and information abouta corresponding coverage enhancement amount (dB). This correspondencemay be predefined after being obtained by means of mathematiccalculation or in an emulation manner. Actual coverage statuses of userequipments differ greatly, not all users that need coverage enhancementneed compensation as large as 20 dB, and an actual case is that thecoverage enhancement amount may be an amount from 0 dB to 20 dB. Inaddition, quantities of transmission time intervals needed by userequipments that need different coverage enhancement amounts aredifferent. User equipment that needs less coverage enhancement needsfewer transmission time intervals because needed coverage enhancementcompensation may be obtained in a shorter accumulated time. Therefore,user equipments that need different coverage enhancements may begrouped, so that user equipments that need equal or close coverageenhancement amounts are clustered to form a group and use a samerepetition count. In this way, a range that is from a coverageenhancement amount of 0 dB to a coverage enhancement amount of 20 dB maybe divided into several groups, such as [5 dB, 10 dB, 15 dB, 20 dB].Certainly, a system may also indiscriminately provide only one coverageenhancement amount, such as 15 dB or 20 dB.

In the prior art, to access a radio communications system, userequipment first performs a cell searching process to search for allpossible cells and find an appropriate cell, and then performs a randomaccess process to access a found target cell. After finding theappropriate cell and establishing downlink synchronization, the userequipment receives system information from a base station serving thetarget cell, where the system information includes a target receivepower for transmitting a preamble sequence (preamble) in an uplinkrandom access process to be performed by a UE.

When the base station receives at the same time signals sent by two userequipments from which distances to the base station are different, andbecause a signal of user equipment closer to the base station isrelatively strong, and a signal of user equipment farther from the basestation is relatively weak, the strong signal of the user equipmentcloser to the base station severely interferes with the signal of theother user equipment, that is, a near-far effect (near-far effect). Amethod for resolving this problem is: adjusting in real time transmitpowers of the user equipments according to different communicationdistances, that is, power control is performed. When the user equipmentinitiates the uplink random access process to access the target basestation, a transmit power of the preamble sequence is determinedaccording to a target receive power of the preamble sequence and anuplink path loss (PL, path loss) between the user equipment and thetarget base station. The uplink PL may be obtained by estimatingaccording to a downlink path loss that is between the target basestation and the user equipment and is measured by the user equipment.

If a same coverage enhancement resource is provided in a system, usersthat need coverage enhancement all use a same quantity of coverageenhancement repetitions (a quantity of transmission time intervals). Forexample, a coverage enhancement of 15 dB is corresponding to 100 timesof repeated transmissions (100 transmission time intervals). However,actual coverage enhancements needed by the user equipments aredifferent. Because uplink path losses are different, some userequipments need only a relatively small coverage enhancement, forexample, only 5 dB may meet a requirement of a target receive power;some user equipments need a relatively large coverage enhancement valueso that the target receive power can be reached. If uplink path lossesof user equipment 1 and user equipment 2 are different, an uplink pathloss of the user equipment 1 is small and a coverage enhancement of 5 dBis needed, an uplink path loss of the user equipment 2 is large and acoverage enhancement of 15 dB is needed, and both the user equipment 1and the user equipment 2 perform transmission by using a maximumtransmit power, powers that are received at each transmission timeinterval by the target base station from the user equipment 1 and theuser equipment 2 are also different, and the near-far effect appears ateach transmission time interval. When the user equipment 1 and the userequipment 2 perform repeated transmission by using a same transmissiontime interval, accumulated total receive powers that are of the userequipment 1 and the user equipment 2 and are collected on a base stationside are also different. If a total receive power accumulated after theuser equipment 2 performs repeated transmission may exactly meet therequirement of the target receive power, a total receive poweraccumulated after the user equipment 1 performs repeated transmission is10 dB (15 dB-5 dB) more than the target receive power. It can be learnedthat for the target base station, in addition to impact of normalreceiving of the user equipment 2 due to the near-far effect, a receivepower of the user equipment 1 is 10 dB higher than the target receivepower, thereby greatly wasting a transmit power of the user equipment 1.

SUMMARY

Implementation manners of the present invention provide a method forsending a preamble sequence and user equipment, so that a problem of anear-far effect that appears at a target base station when differentuser equipments repeatedly send a sequence can be avoided, and atransmit power of user equipment is reduced; in addition, a problem ofsetting a transmit power when coverage enhancement user equipmentperforms power ramping is also resolved.

According to a first aspect, a method for sending a preamble sequence isprovided, where the method includes: determining a transmit power forsending a preamble sequence, where the transmit power meets thefollowing formula: Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL}, where Power is thedetermined transmit power, Pmax is a maximum transmit power of userequipment, PL is an uplink path loss and is obtained by estimatingaccording to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, wherePREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep,and preambleInitialReceivedTargetPower is an initial target receivepower of the preamble sequence, DELTA_PREAMBLE is a power offset basedon a format of the preamble sequence, powerRampingStep is a power rampstep, preamble_transmission_counter is a repetition count fortransmitting the preamble sequence, and X_(i) is a power offsetcorresponding to a preamble sequence resource pool i for coverageenhancement random access; and sending the preamble sequence accordingto the determined transmit power.

With reference to the first aspect, in a first possible implementationmanner of the first aspect, the power offset X_(i) meetsPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

With reference to the first implementation manner of the first aspect,in a second possible implementation manner of the first aspect, themethod further includes: determining the power offset X_(i), where thedetermining the power offset X_(i) includes: searching for the poweroffset X_(i) in ascending order of power offsets, or searching for thepower offset X_(i) in ascending order of repetition counts fortransmitting the preamble sequence.

With reference to the first implementation manner or the secondimplementation manner of the first aspect, in a third possibleimplementation manner of the first aspect, the sending the preamblesequence includes: transmitting the preamble sequence by using arepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access.

With reference to the first implementation manner, the secondimplementation manner, or the third implementation manner of the firstaspect, in a fourth possible implementation manner of the first aspect,the determined transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, or the fourthimplementation manner of the first aspect, in a fifth possibleimplementation manner of the first aspect, the power offset X_(i) is acoverage enhancement amount that is corresponding to the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, the fourthimplementation manner, or the fifth manner of the first aspect, in asixth possible implementation manner of the first aspect, thedetermining a transmit power for sending a preamble sequence includes:obtaining PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter) by performing calculation according tothe power offset X_(i) and sending the preamble sequence according toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter), to perform the preamble_transmission_counter^(th) randomaccess;

if the preamble_transmission_counter^(th) random access fails,increasing preamble_transmission_counter by one, keeping X_(i)unchanged, and calculating the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter); and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, performingtransmission by using the repetition count corresponding to the preamblesequence resource pool i for coverage enhancement random access, wherethe transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, searching for thepower offset X_(i) in ascending order of repetition counts or the poweroffsets X_(i), and determining whether the found power offset X_(i)meets PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ; and if a minimum value ofX_(i) that meets the foregoing formula is found, performing transmissionby using the repetition count corresponding to the preamble sequenceresource pool i for coverage enhancement random access, where thetransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL; or if the foregoing inequalitycannot be met after all X_(i) are traversed, performing transmission byusing a repetition count corresponding to a preamble sequence resourcepool i for coverage enhancement random access that is found at last,where the transmit power is Pmax.

With reference to the first aspect, the first implementation manner, thesecond implementation manner, the third implementation manner, thefourth implementation manner, the fifth implementation manner, or thesixth implementation manner, of the first aspect, in a seventh possibleimplementation manner of the first aspect, information about thepreamble sequence resource pool i for coverage enhancement random accessis obtained from system information, or is preset.

With reference to the seventh possible implementation manner of thefirst aspect, in an eighth possible implementation manner of the firstaspect, the information about the preamble sequence resource pool i forcoverage enhancement random access includes at least one type of thefollowing information: the repetition count corresponding to thepreamble sequence resource pool i for coverage enhancement random accessand a coverage enhancement amount corresponding to the preamble sequenceresource pool i for coverage enhancement random access.

According to a second aspect, user equipment is provided, where the userequipment includes: a determining module, configured to determine atransmit power for sending a preamble sequence, where the transmit powermeets the following formula:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}, where Power is the determinedtransmit power, Pmax is a maximum transmit power of the user equipment,PL is an uplink path loss and is obtained by estimating according to adownlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter) is a target receive power of thepreamble sequence, where PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep,and preambleInitialReceivedTargetPower is an initial target receivepower of the preamble sequence, DELTA_PREAMBLE is a power offset basedon a format of the preamble sequence, powerRampingStep is a power rampstep, preamble_transmission_counter is a repetition count fortransmitting the preamble sequence, and X_(i) is a power offsetcorresponding to a preamble sequence resource pool i for coverageenhancement random access; and a sending module, configured to send thepreamble sequence according to the determined transmit power.

With reference to the implementation manner of the second aspect, in afirst possible implementation manner of the second aspect, the poweroffset X_(i) meets

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

With reference to the first implementation manner of the second aspect,in a second possible implementation manner of the second aspect, thedetermining module is further configured to search for the power offsetX_(i) in ascending order of power offsets, or search for the poweroffset X_(i) in ascending order of repetition counts for transmittingthe preamble sequence.

With reference to the first implementation manner or the secondimplementation manner of the second aspect, in a third possibleimplementation manner of the second aspect, the sending module isfurther configured to transmit the preamble sequence by using arepetition count corresponding to the preamble sequence resource poolfor coverage enhancement random access.

With reference to the first implementation manner, the secondimplementation manner, or the third implementation manner of the secondaspect, in a fourth possible implementation manner of the second aspect,the determined transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, or the fourthimplementation manner of the second aspect, in a fifth possibleimplementation manner of the second aspect, the power offset X_(i) is acoverage enhancement amount that is corresponding to the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, the fourthimplementation manner, or the fifth manner of the second aspect, in asixth possible implementation manner of the second aspect, thedetermining module is specifically configured to obtainPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) by performing calculation according to the power offsetX_(i), and send the preamble sequence according toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter), to perform the preamble_transmission_counter^(th) randomaccess;

if the preamble_transmission_counter^(th) random access fails, increasepreamble_transmission_counter^(th) one, keep X_(i) unchanged, andcalculate the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter); and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, perform transmissionby using the repetition count corresponding to the preamble sequenceresource pool i for coverage enhancement random access, where thetransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, search for thepower offset X_(i) in ascending order of repetition counts or the poweroffsets X_(i), and determine whether the found power offset X_(i) meetsPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, perform transmission by using the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access, where the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, perform transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, where the transmitpower is Pmax.

With reference to the second aspect, the first implementation manner,the second implementation manner, the third implementation manner, thefourth implementation manner, or the fifth manner, in a seventh possibleimplementation manner of the second aspect, information about thepreamble sequence resource pool i for coverage enhancement random accessis obtained from system information, or is preset.

With reference to the seventh possible implementation manner of thesecond aspect, in an eighth possible implementation manner of the secondaspect, the information about the preamble sequence resource pool i forcoverage enhancement random access includes at least one type of thefollowing information: the repetition count corresponding to thepreamble sequence resource pool i for coverage enhancement random accessand a coverage enhancement amount corresponding to the preamble sequenceresource pool i for coverage enhancement random access.

According to a third aspect, user equipment is provided, including aprocessor and a sender, where the processor is configured to execute thefollowing operation by invoking an operation instruction: determining atransmit power for sending a preamble sequence, where the transmit powermeets the following formula:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}, where Power is the determinedtransmit power, Pmax is a maximum transmit power of the user equipment,PL is an uplink path loss and is obtained by estimating according to adownlink path loss, and PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter) is a target receive power of thepreamble sequence, where PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep,and preambleInitialReceivedTargetPower is an initial target receivepower of the preamble sequence, DELTA_PREAMBLE is a power offset basedon a format of the preamble sequence, powerRampingStep is a power rampstep, preamble_transmission_counter is a repetition count fortransmitting the preamble sequence, and X_(i) is a power offsetcorresponding to a preamble sequence resource pool i for coverageenhancement random access; and the sender is configured to send thepreamble sequence according to the determined transmit power.

With reference to the implementation manner of the third aspect, in afirst possible implementation manner of the third aspect, the poweroffset X_(i) meets PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is aconstant and a preset threshold.

With reference to the first implementation manner of the third aspect,in a second possible implementation manner of the third aspect, theprocessor is further configured to search for the power offset X_(i) inascending order of power offsets, or search for the power offset X_(i)in ascending order of repetition counts for transmitting the preamblesequence.

With reference to the first implementation manner or the secondimplementation manner of the third aspect, in a third possibleimplementation manner of the third aspect, the sender is furtherconfigured to transmit the preamble sequence by using a repetition countcorresponding to the preamble sequence resource pool i for coverageenhancement random access.

With reference to the first implementation manner, the secondimplementation manner, or the third implementation manner of the thirdaspect, in a fourth possible implementation manner of the third aspect,the determined transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, or the fourthimplementation manner of the third aspect, in a fifth possibleimplementation manner of the third aspect, the power offset X_(i) is acoverage enhancement amount that is corresponding to the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access.

With reference to the first implementation manner, the secondimplementation manner, the third implementation manner, the fourthimplementation manner, or the fifth manner of the third aspect, in asixth possible implementation manner of the third aspect, the processoris specifically configured to obtain PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter) by performingcalculation according to the power offset X_(i), and send the preamblesequence according to PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter), to perform thepreamble_transmission_counter^(th) random access;

if the preamble_transmission_counter^(th) random access fails, increasepreamble_transmission_counter by one, keep X_(i) unchanged, andcalculate the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter); and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, perform transmissionby using the repetition count corresponding to the preamble sequenceresource pool i for coverage enhancement random access, where thetransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, search for thepower offset X_(i) in ascending order of repetition counts or the poweroffsets X_(i), and determine whether the found power offset X_(i) meetsPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, perform transmission by using the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access, where the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, perform transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, where the transmitpower is Pmax.

With reference to the third aspect, the first implementation manner, thesecond implementation manner, the third implementation manner, thefourth implementation manner, or the fifth manner, in a seventh possibleimplementation manner of the third aspect, information about thepreamble sequence resource pool i for coverage enhancement random accessis obtained from system information, or is preset.

With reference to the seventh possible implementation manner of thethird aspect, in an eighth possible implementation manner of the thirdaspect, the information about the preamble sequence resource pool i forcoverage enhancement random access includes at least one type of thefollowing information: the repetition count corresponding to thepreamble sequence resource pool i for coverage enhancement random accessand a coverage enhancement amount corresponding to the preamble sequenceresource pool i for coverage enhancement random access.

Beneficial effects in the implementation manners of the presentinvention are as follows: When user equipment performs transmission byusing a preamble sequence resource pool for coverage enhancement randomaccess, during transmit power calculation, a power offset is introduced,that is, a power gain brought by means of repeated transmissionperformed by using the preamble sequence resource pool for coverageenhancement random access is introduced, and the gain is converted forthe transmit power calculation. Because the repeated transmission itselfbrings a coverage enhancement amount X dB, when a target receive powerof a preamble sequence is calculated, the gain is deducted, andPREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep,that is, the target receive power of the preamble sequence may becorrespondingly decreased by X dB. After such calculation is performed,according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is alsocorrespondingly decreased by X dB, and a transmit powerPower=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated.For user equipments whose coverage enhancement requirements are lessthan or equal to X dB, that is, all users who meetPREAMBLE_RECEIVED_TARGET_POWER+PL−Pmax≦X, becausePREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased byX dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than Pmax,that is, according to calculation of the formula, a transmit power isPREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured thatreceive powers received on a base station side are close to each otherand are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-fareffect. Likewise, all user equipments whose coverage enhancementrequirements are less than or equal to X dB perform transmissionaccording to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, sothat a path loss is overcome, a same target receive power is achieved,and no power is wasted.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflyintroduces the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show some embodiments of the presentinvention, and a person of ordinary skill in the art may still deriveother drawings from these accompanying drawings without creativeefforts.

FIG. 1 is a schematic diagram in which in the prior art, user equipmentrepeatedly sends a sequence, and powers collected in a correspondingresource pool by a target base station are different;

FIG. 2 is a flowchart of an implementation manner of a method forsending a preamble sequence according to the present invention;

FIG. 3 is a schematic structural diagram of a first implementationmanner of user equipment according to the present invention; and

FIG. 4 is a schematic structural diagram of a second implementationmanner of user equipment according to the present invention.

DETAILED DESCRIPTION

The following describes the present invention in detail with referenceto the accompanying drawings and implementation manners.

Referring to FIG. 2, FIG. 2 is a flowchart of an implementation mannerof the method sending a preamble sequence according to the presentinvention. As shown in FIG. 2, the method includes the following steps:

Step 201: Determine a transmit power for sending a preamble sequence,where the transmit power is as follows:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}

Power is the determined transmit power, Pmax is a maximum transmit powerof user equipment, PL is a path loss value obtained by estimatingaccording to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, where

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

preambleInitialReceivedTargetPower is an initial target receive power ofthe preamble sequence, where the initial target receive power of thepreamble sequence may be notified by a target base station by usingsystem information, and the initial target receive powerpreambleInitialReceivedTargetPower of the preamble sequence may be setto −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a poweroffset based on a format of the preamble sequence, and values are shownin the following table:

Values of DELTA_PREAMBLE Format of a preamble sequence Value ofDELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB 3 −3 dB 4 8 dB

X_(i) is a power offset corresponding to a preamble sequence resourcepool i for coverage enhancement random access.preamble_transmission_counter is a repetition count for transmitting thepreamble sequence, where preamble_transmission_counter ε{1, 2, . . . ,preambleTransMax} and is set to 1 during initial access, andpreambleTransMax is a system parameter and is a maximum transmissioncount of the preamble sequence. powerRampingStep is a power ramp step,where the power ramp step may be notified by the target base station byusing the system information, and the power ramp step powerRampingStepthat is of the preamble sequence and is broadcast by the target basestation may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

It can be learned from the foregoing MIN formula that, whenPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL is less than Pmax, a transmit power value of the preamblesequence of the user equipment is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; otherwise, a transmit power value of the preamblesequence of the user equipment is set to Pmax.

For X_(i) it should further be noted that, information that is used fora preamble sequence resource pool for coverage enhancement random accessand is set by the base station includes a corresponding repetition count(that is, occupied transmission time intervals) and/or information abouta corresponding coverage enhancement amount (dB), and may be obtained bynotifying the system information of the base station, or may be obtainedin a predefined manner. The information about the preamble sequenceresource pool for coverage enhancement random access includes thecorresponding repetition count R, that is, a quantity of the occupiedtransmission time intervals, and/or the information X about thecorresponding coverage enhancement amount (dB), and there is acorrespondence between the repetition count, that is, the quantity ofthe occupied transmission time intervals, corresponding to the preamblesequence resource pool for coverage enhancement random access, and thecorresponding coverage enhancement amount (dB). Therefore, theinformation can still be finally obtained even if the information aboutthe coverage enhancement amount (dB) does not exist.

The power offset X_(i) is a coverage enhancement amount corresponding tothe preamble sequence resource pool i for coverage enhancement randomaccess, or the power offset X_(i) is a coverage enhancement amount thatis corresponding to the repetition count, that is, occupied transmissiontime intervals, corresponding to the preamble sequence resource pool ifor coverage enhancement random access. Further, the power offset X_(i)is obtained from the information about the preamble sequence resourcepool for coverage enhancement random access, where the information aboutthe preamble sequence resource pool for coverage enhancement randomaccess is obtained by notifying the system information, or is obtainedin a manner predefined by a current device.

In an implementation manner of the present invention, the target receivepower preambleInitialReceivedTargetPower, in the system information, ofthe preamble sequence resource pool for coverage enhancement randomaccess may be defined, so that the target receive power includes thecoverage enhancement amount X dB. For example, for common userequipment, an initial target receive power of a preamble sequenceresource pool for random access is preambleInitialReceivedTargetPowerand a target receive power of a preamble sequence resource pool forcoverage enhancement random access ispreambleInitialReceivedTargetPower−X where X is a power offset; then:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(preamble_transmission_counter−1)*powerRampingStep.

In another implementation of the present invention, if the initialtarget receive power that is of the preamble sequence and is broadcastby a system is preambleInitialReceivedTargetPower, the target receivepower of the preamble sequence resource pool for coverage enhancementrandom access is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(preamble_transmission_counter−1)*powerRampingStep.

In this case, the power offset X is a coverage enhancement amount. Theuser equipment needs to use the preamble sequence resource pool forcoverage enhancement random access; and a transmit power of the userequipment at each transmission time interval is:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

min{ } is a MIN function, and Pmax is the maximum transmit power of theuser equipment.

PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of thepreamble sequence resource pool.

X is the power offset corresponding to the preamble sequence resourcepool, that is, the coverage enhancement amount (dB)

PL is a path loss value obtained by estimating according to the downlinkpath loss. More generally, the base station may set N preamble sequenceresource pools for coverage enhancement random access, where N is apositive integer. Each preamble sequence resource pool for coverageenhancement random access includes a corresponding repetition count,that is, occupied transmission time intervals, and/or information abouta corresponding coverage enhancement amount (dB) that is represented byX_(i), where iε{1, . . . , N}, that is, there are at least two poweroffsets X_(i). For ease of description, the preamble sequence resourcepool for coverage enhancement random access is referred to as a preamblesequence resource pool for short in the following.

If the initial target receive power of the preamble sequence of a systemis preambleInitialReceivedTargetPower, a target receive power of thei^(th) preamble sequence resource pool for coverage enhancement randomaccess is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts (occupied transmission time intervals) are {R₁, . . ., R_(N)}, and power offsets corresponding to the first preamble sequenceresource pool for coverage enhancement random access to the N^(th)preamble sequence resource pool for coverage enhancement random accessare {X₁, . . . , X_(N)}. A definition of a power offset is a coverageenhancement amount corresponding to the resource, or may be any poweroffset defined by the system.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, the power ramp step ispowerRampingStep, and generally, when the first random access isinitiated and preamble_transmission_counter=1, step 201 may further bespecifically as follows:

during transmit power calculation, superposing power offsets inascending order or descending order of repetition counts R or poweroffsets X; and stopping until X_(i) that meets the following formula isfound according to calculation of the following formulas, or if thefollowing inequality cannot be met after all R_(i) or X_(i) aretraversed, performing transmission according to the maximum transmitpower Pmax, where:

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0, and Δ is aconstant and a preset threshold.

If the user equipment uses the preamble sequence resource pool i forcoverage enhancement random access, during initial access of the userequipment, a transmit power at each transmission time interval is:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL} [dBm].

However, it is not ensured that successful access can be implementedwhen the first random access is initiated, and successful access may beimplemented only after power ramping is performed. In an originalresource pool, a target power requirement that is imposed after powerramping is performed may be met; and the resource pool does not need tobe changed. Alternatively, in an original resource pool, a target powerrequirement that is imposed after power ramping is performed cannot bemet; and the resource pool need to be changed to a resource poolcorresponding to a larger repetition count/a larger coverage enhancementamount. Therefore, the following uses an example of multiple times ofrandom access so as to ensure that a process thereof can be clearlydescribed.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts are {R₁, . . . , R_(N)}, and power offsetscorresponding to the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access are {X₁, . . . , X_(N)}. Adefinition of a power offset is a coverage enhancement amountcorresponding to the resource, or may be any power offset defined by thesystem due to coverage enhancement.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, and the power rampstep is powerRampingStep, when preamble_transmission_counter=1, aprocedure is as follows:

During transmit power calculation, the user equipment superposes poweroffsets in ascending order of repetition counts R{R₁, . . . , R_(N)} orpower offsets X{X₁, . . . , X_(N)}; and may stop until X_(i) that meetsthe following formula is found according to calculation of the followingformulas, or if the following inequality cannot be met after all R_(i)or X_(i) are traversed, perform transmission according to the maximumtransmit power Pmax, where

an initial value of preamble_transmission_counter is 1; and

the following is calculated in ascending order of X_(i):

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0, and Δ is aconstant and a preset threshold.

When the foregoing inequality is met, calculation is stopped, thepreamble sequence resource pool i for coverage enhancement random accessis selected, and the transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL [dBm]; or the inequality is notmet after all X_(i) are traversed, and the transmit power of thepreamble sequence is set to Pmax.

Step 202: Send the preamble sequence according to the determinedtransmit power.

Further, if the user equipment has not received a response from the basestation side within a set time window after sending the preamblesequence, it is considered that current transmission fails.preamble_transmission_counter=preamlbe_transmission_counter+1, wherepreamble_transmission_counter ε{1, 2, . . . , preambleTransMax}. Powerramping (power ramping) is performed according to the power ramp steppowerRampingStep broadcast by the system. According to the formulas,first, it is assumed that the preamble sequence resource pool forcoverage enhancement random access is not changed, that is, X_(i) is notchanged, and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

If the inequality is still met, the preamble sequence resource pool ifor coverage enhancement random access continues to be selected. Atarget receive power that is of the preamble sequence and iscorresponding to preamble_transmission_counter (that is alreadyincreased by 1 for itself) in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(Preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL [dBm].

If the inequality cannot be met, i=i+1, the preamble sequence resourcepool for coverage enhancement random access is changed in ascendingorder of X_(i), and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

Until the inequality is met, a preamble sequence resource pool forcoverage enhancement random access corresponding to X_(i) in this caseis selected. A target receive power that is of the preamble sequence andis corresponding to preamble_transmission_counter in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set to(PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission)^(_) ^(counter)) [dBm].

Alternatively, the inequality is not met after all X_(i) are traversed,and the transmit power of the preamble sequence is set to Pmax.

In brief, step 201 may also include:

obtaining the transmit power according to the power offset X_(i), andsending the preamble sequence according to the transmit power, toperform the preamble_transmission_counter^(th) random access;

if the preamble_transmission_counter^(th) random access fails, makingpreamble_transmission_counter=preamlbe_transmission_counter+1, keepingX_(i) unchanged, and calculating the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, performingtransmission by using the repetition count corresponding to the preamblesequence resource pool i for coverage enhancement random access, wherethe transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, searching for thepower offset X_(i) in ascending order of repetition counts, that is,occupied transmission time intervals, or the power offsets X_(i), anddetermining whether the found power offset X_(i) meets thatPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, performing transmission by using therepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access, where the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, performing transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, where the transmitpower is Pmax, and Δ≧0, and Δ is a constant and a preset threshold.

In this implementation manner of the present invention, when userequipment performs transmission by using a preamble sequence resourcepool for coverage enhancement random access, during transmit powercalculation, a power offset is introduced, that is, a power gain broughtby means of repeated transmission performed by using the preamblesequence resource pool for coverage enhancement random access isintroduced, and the gain is converted for the transmit powercalculation. Because the repeated transmission itself brings a coverageenhancement amount (dB) X, when a target receive power of a preamblesequence is calculated, the gain is deducted, and

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

That is, the target receive power of the preamble sequence may becorrespondingly decreased by X dB. After such calculation is performed,according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is alsocorrespondingly decreased by X dB, and a transmit powerPower=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated.For user equipments whose coverage enhancement requirements are lessthan or equal to X dB, that is, all users who meetPREAMBLE_RECEIVED_TARGET_POWER+PL−Pmax≦X, becausePREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased byX dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than Pmax,that is, according to calculation of the formulas, a transmit power isPREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured thatreceive powers received on a base station side are close to each otherand are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-fareffect. Likewise, all user equipments whose coverage enhancementrequirements are less than or equal to X dB perform transmissionaccording to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, sothat a path loss is overcome, a same target receive power is achieved,and no power is wasted.

Referring to FIG. 3, FIG. 3 is a schematic structural diagram of a firstimplementation manner of user equipment according to the presentinvention. As shown in FIG. 3, user equipment 30 includes a determiningmodule 301 and a sending module 302.

The determining module 301 is configured to determine a transmit powerfor sending a preamble sequence, where the transmit power meets thefollowing formula:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}

Power is the determined transmit power, Pmax is a maximum transmit powerof the user equipment, PL is a path loss value obtained by estimatingaccording to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, where

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

preambleInitialReceivedTargetPower is an initial target receive power ofthe preamble sequence, where the initial target receive power of thepreamble sequence may be notified by a target base station by usingsystem information, and the initial target receive powerpreambleInitialReceivedTargetPower of the preamble sequence may be setto −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a poweroffset based on a format of the preamble sequence, and values are shownin the following table:

Values of DELTA_PREAMBLE Format of a preamble sequence Value ofDELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB 3 −3 dB 4 8 dB

X_(i) is a power offset corresponding to a preamble sequence resourcepool i for coverage enhancement random access.preamble_transmission_counter is a repetition count for transmitting thepreamble sequence, where preamble_transmission_counter ε{1, 2, . . . ,preambleTransMax} and is set to 1 during initial access, andpreambleTransMax is a system parameter and is a maximum transmissioncount of the preamble sequence. powerRampingStep is a power ramp step,where the power ramp step may be notified by the target base station byusing the system information, and the power ramp step powerRampingStepthat is of the preamble sequence and is broadcast by the target basestation may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

It can be learned from the foregoing MIN formula that, whenPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL is less than Pmax, a transmit power value of the preamblesequence of the user equipment is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; otherwise, a transmit power value of the preamblesequence of the user equipment is set to Pmax.

For X_(i), it should further be noted that, information that is used fora preamble sequence resource pool for coverage enhancement random accessand is set by the base station includes a corresponding repetition count(that is, occupied transmission time intervals) and/or information abouta corresponding coverage enhancement amount (dB), and may be obtained bynotifying the system information of the base station, or may be obtainedin a predefined manner. The information about the preamble sequenceresource pool for coverage enhancement random access includes thecorresponding repetition count R, that is, a quantity of the occupiedtransmission time intervals, and/or the information X about thecorresponding coverage enhancement amount (dB), and there is acorrespondence between the repetition count, that is, the quantity ofthe occupied transmission time intervals, corresponding to the preamblesequence resource pool for coverage enhancement random access, and thecorresponding coverage enhancement amount (dB). Therefore, theinformation can still be finally obtained even if the information aboutthe coverage enhancement amount (dB) does not exist.

The power offset X_(i) is a coverage enhancement amount corresponding tothe preamble sequence resource pool i for coverage enhancement randomaccess, or the power offset X_(i) is a coverage enhancement amount thatis corresponding to the repetition count, that is, occupied transmissiontime intervals, corresponding to the preamble sequence resource pool ifor coverage enhancement random access. Further, the power offset X_(i)is obtained from the information about the preamble sequence resourcepool for coverage enhancement random access, where the information aboutthe preamble sequence resource pool for coverage enhancement randomaccess is obtained by notifying the system information, or is obtainedin a manner predefined by a current device.

In an implementation of the present invention, the target receive powerpreambleInitialReceivedTargetPower, in the system information, of thepreamble sequence resource pool for coverage enhancement random accessmay be defined, so that the target receive power includes the coverageenhancement amount (dB) X. For example, for common user equipment, aninitial target receive power of a preamble sequence resource pool forrandom access is preambleInitialReceivedTargetPower, and a targetreceive power of a preamble sequence resource pool for coverageenhancement random access is preambleInitialReceivedTargetPower−X, whereX is a power offset; then:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE+(preamble_(—)transmission_counter−1)*powerRampingStep.

In another implementation of the present invention, if the initialtarget receive power that is of the preamble sequence and is broadcastby a system is preambleInitialReceivedTargetPower, the target receivepower of the preamble sequence resource pool for coverage enhancementrandom access is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X+(preamble_transmission_counter−1)*powerRampingStep.

In this case, the power offset X is a coverage enhancement amount. Theuser equipment needs to use the preamble sequence resource pool forcoverage enhancement random access; and a transmit power of the userequipment at each transmission time interval is:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

min{ } is a MIN function, and Pmax is the maximum transmit power of theuser equipment.

PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of thepreamble sequence resource pool.

X is the power offset corresponding to the preamble sequence resourcepool, that is, the coverage enhancement amount (dB).

PL is a path loss value obtained by estimating according to the downlinkpath loss. More generally, the base station may set N preamble sequenceresource pools for coverage enhancement random access, where N is apositive integer. Each preamble sequence resource pool for coverageenhancement random access includes a corresponding repetition count,that is, occupied transmission time intervals, and/or information abouta corresponding coverage enhancement amount (dB) that is represented byX_(i), where iε{1, . . . , N}, that is, there are at least two poweroffsets X_(i). For ease of description, the preamble sequence resourcepool for coverage enhancement random access is referred to as a preamblesequence resource pool for short in the following.

If the initial target receive power of the preamble sequence of a systemis preambleInitialReceivedTargetPower a target receive power of thei^(th) preamble sequence resource pool for coverage enhancement randomaccess is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts are {R₁, . . . , R_(N)}, and power offsetscorresponding to the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access are {X₁, . . . , X_(N)}. Adefinition of a power offset is a coverage enhancement amountcorresponding to the resource, or may be any power offset defined by thesystem.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, the power ramp step ispowerRampingStep, and generally, when the first random access isinitiated and preamble_transmission_counter=1, the determining module301 may further be specifically as follows:

during transmit power calculation, superposing power offsets inascending order or descending order of repetition counts R or poweroffsets X; and stopping until X_(i) that meets the following formula isfound according to calculation of the following formulas, or if thefollowing inequality cannot be met after all R_(i) or X_(i) aretraversed, performing transmission according to the maximum transmitpower Pmax, where:

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_(—)transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0, and Δ is aconstant and a preset threshold.

If the user equipment uses the preamble sequence resource pool i forcoverage enhancement random access, during initial access of the userequipment, a transmit power at each transmission time interval is:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL} [dBm].

However, it is not ensured that successful access can be implementedwhen the first random access is initiated, and successful access may beimplemented only after power ramping is performed. In an originalresource pool, a target power requirement that is imposed after powerramping is performed may be met; and the resource pool does not need tobe changed. Alternatively, in an original resource pool, a target powerrequirement that is imposed after power ramping is performed cannot bemet; and the resource pool needs to be changed to a resource poolcorresponding to a larger repetition count/a larger coverage enhancementamount. Therefore, the following uses an example of multiple times ofrandom access so as to ensure that a process thereof can be clearlydescribed.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts are {R₁, . . . , R_(N)}, and power offsetscorresponding to the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access are {X₁, . . . , X_(N)}. Adefinition of a power offset is a coverage enhancement amountcorresponding to the resource, or may be any power offset defined by thesystem due to coverage enhancement.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, and the power rampstep is powerRampingStep, when preamble_transmission_counter=1, aprocedure is as follows:

During transmit power calculation, the user equipment superposes poweroffsets in ascending order of repetition counts R{R₁, . . . , R_(N)} orpower offsets X{X₁, . . . , X_(N)}; and may stop until X_(i) that meetsthe following formula is found according to calculation of the followingformulas, or if the following inequality cannot be met after all R_(i)or X_(i) are traversed, perform transmission according to the maximumtransmit power Pmax, where

an initial value of preamble_transmission_counter is 1; and

the following is calculated in ascending order of X_(i):

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0, and Δ is aconstant and a preset threshold.

When the foregoing inequality is met, calculation is stopped, thepreamble sequence resource pool i for coverage enhancement random accessis selected, and the transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL [dBm]; or the inequality is notmet after all X_(i) are traversed, and the transmit power of thepreamble sequence is set to Pmax.

The sending module 302 is configured to send the preamble sequenceaccording to the determined transmit power.

Further, if the user equipment 30 has not received a response from thebase station side within a set time window after sending the preamblesequence, it is considered that current transmission fails.preamble_transmission_counter=preamlbe_transmission_counter+1, wherepreamble_transmission_counter ε{1, 2, . . . , preambleTransMax}. Powerramping (power ramping) is performed according to the power ramp steppowerRampingStep broadcast by the system. According to the formulas,first, it is assumed that the preamble sequence resource pool forcoverage enhancement random access is not changed, that is, X_(i) is notchanged, and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

If the inequality is still met, the preamble sequence resource pool ifor coverage enhancement random access continues to be selected. Thetarget receive power that is of the preamble sequence and iscorresponding to preamble_transmission_counter (that is alreadyincreased by 1 for itself) in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL [dBm].

If the inequality cannot be met, i=i+1, the preamble sequence resourcepool for coverage enhancement random access is changed in ascendingorder of X_(i), and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_(—)transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

Until the inequality is met, a preamble sequence resource pool forcoverage enhancement random access corresponding to X_(i) in this caseis selected. The target receive power that is of the preamble sequenceand is corresponding to preamble_transmission_counter (that is alreadyincreased by 1 for itself) in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set to(PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission)^(_) ^(counter)) [dBm].

Alternatively, the inequality is not met after all X_(i) are traversed,and the transmit power of the preamble sequence is set to Pmax.

In brief, the determining module 301 may also be specifically configuredto: obtain the transmit power according to the power offset X_(i), andsend the preamble sequence according to the transmit power, to performthe preamble_transmission_counter^(th) random access;

if the preamble_transmission_counter^(th) random access fails, makepreamble_transmission_counter=preamlbe_transmission_counter+1, keepX_(i) unchanged, and calculate the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, perform transmissionby using the repetition count corresponding to the preamble sequenceresource pool i for coverage enhancement random access, where thetransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, search for thepower offset X_(i) in ascending order of repetition counts, that is,occupied transmission time intervals, or the power offsets X_(i), anddetermine whether the found power offset X_(i) meets thatPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, performing transmission by using therepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access, where the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, performing transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, where the transmitpower is Pmax, and Δ≧0, and Δ is a constant and a preset threshold.

In this implementation manner of the present invention, when the userequipment performs transmission by using a preamble sequence resourcepool for coverage enhancement random access, during transmit powercalculation, a power offset is introduced, that is, a power gain broughtby means of repeated transmission performed by using the preamblesequence resource pool for coverage enhancement random access isintroduced, and the gain is converted for the transmit powercalculation. Because the repeated transmission itself brings a coverageenhancement amount (dB) X, when a target receive power of a preamblesequence is calculated, the gain is deducted, and

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

That is, the target receive power of the preamble sequence may becorrespondingly decreased by X dB. After such calculation is performed,according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is alsocorrespondingly decreased by X dB; and a transmit powerPower=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated.For user equipments whose coverage enhancement requirements are lessthan or equal to X dB, that is, all users who meetPREAMBLE_RECEIVED_TARGET_POWER+PL−Pmax≦X, becausePREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased byX dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than Pmax,that is, according to calculation of the formulas, a transmit power isPREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured thatreceive powers received on a base station side are close to each otherand are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-fareffect. Likewise, all user equipments whose coverage enhancementrequirements are less than or equal to X dB perform transmissionaccording to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, sothat a path loss is overcome, a same target receive power is achieved,and no power is wasted.

Referring to FIG. 4, FIG. 4 is a schematic structural diagram of asecond implementation manner of user equipment according to the presentinvention. As shown in FIG. 4, user equipment 40 includes a processor401 and a sender 402.

The processor 401 is configured to execute the following operation byusing an operation instruction:

determining a transmit power for sending a preamble sequence, where thetransmit power meets the following formula:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}

Power is the determined transmit power, Pmax is a maximum transmit powerof the user equipment, PL is a path loss value obtained by estimatingaccording to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, where

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

preambleInitialReceivedTargetPower is an initial target receive power ofthe preamble sequence, where the initial target receive power of thepreamble sequence may be notified by a target base station by usingsystem information, and the initial target receive powerpreambleInitialReceivedTargetPower of the preamble sequence may be setto −120 dBm, −118 dBm, −116 dBm, or the like. DELTA_PREAMBLE is a poweroffset based on a format of the preamble sequence, and values are shownin the following table:

Values of DELTA_PREAMBLE Format of a preamble sequence Value ofDELTA_PREAMBLE 0 0 dB 1 0 dB 2 −3 dB 3 −3 dB 4 8 dB

X_(i) is a power offset corresponding to a preamble sequence resourcepool i for coverage enhancement random access.preamble_transmission_counter is a repetition count for transmitting thepreamble sequence, where preamble_transmission_counter ε{1, 2, . . . ,preambleTransMax} and is set to 1 during initial access, andpreambleTransMax is a system parameter and is a maximum transmissioncount of the preamble sequence. powerRampingStep is a power ramp step,where the power ramp step may be notified by the target base station byusing the system information, and the power ramp step powerRampingStepthat is of the preamble sequence and is broadcast by the target basestation may be set to 0 dB, 2 dB, 4 dB, 6 dB, or the like.

It can be learned from the foregoing MIN formula that, whenPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL is less than Pmax, a transmit power value of the preamblesequence of the user equipment is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; otherwise, a transmit power value of the preamblesequence of the user equipment is set to Pmax.

For X_(i), should further be noted that, information that is used for apreamble sequence resource pool for coverage enhancement random accessand is set by the base station includes a corresponding repetition count(that is, occupied transmission time intervals) and/or information abouta corresponding coverage enhancement amount (dB), and may be obtained bynotifying the system information of the base station, or may be obtainedin a predefined manner. The information about the preamble sequenceresource pool for coverage enhancement random access includes thecorresponding repetition count R, that is, a quantity of the occupiedtransmission time intervals, and/or the information X about thecorresponding coverage enhancement amount (dB), and there is acorrespondence between the repetition count, that is, the quantity ofthe occupied transmission time intervals, corresponding to the preamblesequence resource pool for coverage enhancement random access, and thecorresponding coverage enhancement amount (dB). Therefore, theinformation can still be finally obtained even if the information aboutthe coverage enhancement amount (dB) does not exist.

The power offset X_(i) is a coverage enhancement amount corresponding tothe preamble sequence resource pool i for coverage enhancement randomaccess, or the power offset X_(i) is a coverage enhancement amount thatis corresponding to the repetition count, that is, occupied transmissiontime intervals, corresponding to the preamble sequence resource pool ifor coverage enhancement random access. Further, the power offset X_(i)is obtained from the information about the preamble sequence resourcepool for coverage enhancement random access, where the information aboutthe preamble sequence resource pool for coverage enhancement randomaccess is obtained by notifying the system information, or is obtainedin a manner predefined by a current device.

In another implementation of the present invention, if the initialtarget receive power that is of the preamble sequence and is broadcastby a system is preambleInitialReceivedTargetPower, the target receivepower of the preamble sequence resource pool for coverage enhancementrandom access is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X+(preamble_transmission_counter−1)*powerRampingStep.

In this case, the power offset X is a coverage enhancement amount. Theuser equipment needs to use the preamble sequence resource pool forcoverage enhancement random access; and a transmit power of the userequipment at each transmission time interval is:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dBm], where

min{ } is a MIN function, and Pmax is the maximum transmit power of theuser equipment.

PREAMBLE_RECEIVED_TARGET_POWER is the target receive power of thepreamble sequence resource pool.

X is the power offset corresponding to the preamble sequence resourcepool, that is, the coverage enhancement amount (dB).

PL is a path loss value obtained by estimating according to the downlinkpath loss. More generally, the base station may set N preamble sequenceresource pools for coverage enhancement random access, where N is apositive integer. Each preamble sequence resource pool for coverageenhancement random access includes a corresponding repetition count,that is, occupied transmission time intervals, and/or information abouta corresponding coverage enhancement amount (dB) that is represented byX_(i), where iε{1, . . . , N}, that is, there are at least two poweroffsets X_(i). For ease of description, the preamble sequence resourcepool for coverage enhancement random access is referred to as a preamblesequence resource pool for short in the following.

If the initial target receive power of the preamble sequence of a systemis preambleInitialReceivedTargetPower, a target receive power of thei^(th) preamble sequence resource pool for coverage enhancement randomaccess is as follows:

PREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts (occupied transmission time intervals) are {R₁, . . ., R_(N)}, and power offsets corresponding to the first preamble sequenceresource pool for coverage enhancement random access to the N^(th)preamble sequence resource pool for coverage enhancement random accessare {X₁, . . . , X_(N)}. A definition of a power offset is a coverageenhancement amount corresponding to the resource, or may be any poweroffset defined by the system.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, the power ramp step ispowerRampingStep, and generally, when the first random access isinitiated and preamble_transmission_counter=1, step 201 may further bespecifically as follows:

during transmit power calculation, superposing power offsets inascending order or descending order of repetition counts R or poweroffsets X; and stopping until X_(i) that meets the following formula isfound according to calculation of the following formulas, or if thefollowing inequality cannot be met after all R_(i) or X_(i) aretraversed, performing transmission according to the maximum transmitpower Pmax, where:

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0.

If the user equipment uses the preamble sequence resource pool i forcoverage enhancement random access, during initial access of the userequipment, a transmit power at each transmission time interval is:

Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL} [dBm].

However, it is not ensured that successful access can be implementedwhen the first random access is initiated, and successful access may beimplemented only after power ramping is performed. In an originalresource pool, a target power requirement that is imposed after powerramping is performed may be met; and the resource pool does not need tobe changed. Alternatively, in an original resource pool, a target powerrequirement that is imposed after power ramping is performed cannot bemet; and the resource pool needs to be changed to a resource poolcorresponding to a larger repetition count/a larger coverage enhancementamount. Therefore, the following uses an example of multiple times ofrandom access so as to ensure that a process thereof can be clearlydescribed.

It is assumed that there are N preamble sequence resource pools forcoverage enhancement random access in the system, where N is a positiveinteger. From the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access, corresponding sequencerepetition counts are {R₁, . . . , R_(N)}, and power offsetscorresponding to the first preamble sequence resource pool for coverageenhancement random access to the N^(th) preamble sequence resource poolfor coverage enhancement random access are {X₁, . . . , X_(N)}. Adefinition of a power offset is a coverage enhancement amountcorresponding to the resource, or may be any power offset defined by thesystem due to coverage enhancement.

If the initial target receive power of the preamble sequence defined bythe system is preambleInitialReceivedTargetPower, and the power rampstep is powerRampingStep, when preamble_transmission_counter=1, aprocedure is as follows:

During transmit power calculation, the user equipment superposes poweroffsets in ascending order of repetition counts R{R₁, . . . , R_(N)} orpower offsets X{X₁, . . . , X_(N)}; and may stop until X_(i) that meetsthe following formula is found according to calculation of the followingformulas, or if the following inequality cannot be met after all R_(i)or X_(i) are traversed, perform transmission according to the maximumtransmit power Pmax, where

an initial value of preamble_transmission_counter is 1; and

the following is calculated in ascending order of X_(i):

PREAMBLE_RECEIVED_TARGET_POWER_(i)¹=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL−Pmax≦Δ, where Δ≧0.

When the foregoing inequality is met, calculation is stopped, thepreamble sequence resource pool i for coverage enhancement random accessis selected, and the transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ¹+PL [dBm]; or the inequality is notmet after all X_(i) are traversed, and the transmit power of thepreamble sequence is set to Pmax.

The sender 402 is configured to send the preamble sequence according tothe determined transmit power.

Further, if the user equipment has not received a response from the basestation side within a set time window after sending the preamblesequence, it is considered that current transmission fails.preamble_transmission_counter=preamlbe_transmission_counter+1, wherepreamble_transmission_counter ε{1, 2, . . . , preambleTransMax}. Powerramping (power ramping) is performed according to the power ramp steppowerRampingStep broadcast by the system. According to the formulas,first, it is assumed that the preamble sequence resource pool forcoverage enhancement random access is not changed, that is, X_(i) is notchanged, and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

If the inequality is still met, the preamble sequence resource pool ifor coverage enhancement random access continues to be selected. Atarget receive power that is of the preamble sequence and iscorresponding to preamble_transmission_counter (that is alreadyincreased by 1 for itself) in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL [dbm].

If the inequality cannot be met, i=i+1, the preamble sequence resourcepool for coverage enhancement random access is changed in ascendingorder of X_(i), and the calculation is performed again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, where Δ≧0, and Δ is a constant and a presetthreshold.

Until the inequality is met, a preamble sequence resource pool forcoverage enhancement random access corresponding to X_(i) in this caseis selected. A target receive power that is of the preamble sequence andis corresponding to preamble_transmission_counter in this case isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter). The transmit power of the preamble sequence is set to(PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission)^(_) ^(counter)) [dBm].

Alternatively, the inequality is not met after all X_(i) are traversed,and the transmit power of the preamble sequence is set to Pmax.

In brief, the processor 401 may also include:

obtaining the transmit power according to the power offset X_(i), andsending the preamble sequence according to the transmit power, toperform the preamble_transmission_counter^(th) random access;

if the preamble_transmission_counter^(th) random access fails, makingpreamble_transmission_counter=preamlbe_transmission_counter+1, keepingX_(i) unchanged, and calculating the following again:

PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep; and

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met, performingtransmission by using the repetition count corresponding to the preamblesequence resource pool i for coverage enhancement random access, wherethe transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble)^(_) ^(transmission) ^(_) ^(counter)+PL; or

if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met, searching for thepower offset X_(i) in ascending order of repetition counts, that is,occupied transmission time intervals, or the power offsets X_(i), anddetermining whether the found power offset X_(i) meets thatPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, performing transmission by using therepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access, where the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, performing transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, where the transmitpower is Pmax, and Δ≧0, and Δ is a constant and a preset threshold.

The processor 401 controls an operation of the user equipment 40, andthe processor 401 may also be referred to as a CPU (Central ProcessingUnit, central processing unit). In a specific application, components ofthe user equipment 40 are coupled together by using a bus system 403,where in addition to a data bus, the bus system 403 may further includea power bus, a control bus, a status signal bus, and the like. However,for clear description, various types of buses in the figure are markedas the bus system 403.

In this implementation manner of the present invention, when the userequipment performs transmission by using a preamble sequence resourcepool for coverage enhancement random access, during transmit powercalculation, a power offset is introduced, that is, a power gain broughtby means of repeated transmission performed by using the preamblesequence resource pool for coverage enhancement random access isintroduced, and the gain is converted for the transmit powercalculation. Because the repeated transmission itself brings a coverageenhancement amount (dB) X, when a target receive power of a preamblesequence is calculated, the gain is deducted, andPREAMBLE_RECEIVED_TARGET_POWER=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep,that is, the target receive power of the preamble sequence may becorrespondingly decreased by X dB. After such calculation is performed,according to the prior art, PREAMBLE_RECEIVED_TARGET_POWER+PL is alsocorrespondingly decreased by X dB; and a transmit powerPower=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER+PL} [dbm] is calculated.For user equipments whose coverage enhancement requirements are lessthan or equal to X dB, that is, all users who meetPREAMBLE_RECEIVED_TARGET_POWER+PL−Pmax≦X, becausePREAMBLE_RECEIVED_TARGET_POWER+PL has been correspondingly decreased byX dB, in this case, PREAMBLE_RECEIVED_TARGET_POWER+PL is less than Pmax,that is, according to calculation of the formulas, a transmit power isPREAMBLE_RECEIVED_TARGET_POWER+PL. In this way, it may be ensured thatreceive powers received on a base station side are close to each otherand are PREAMBLE_RECEIVED_TARGET_POWER, thereby overcoming a near-fareffect. Likewise, all user equipments whose coverage enhancementrequirements are less than or equal to X dB perform transmissionaccording to the transmit power: PREAMBLE_RECEIVED_TARGET_POWER+PL, sothat a path loss is overcome, a same target receive power is achieved,and no power is wasted.

The foregoing descriptions are merely implementation manners of thepresent invention, and are not intended to limit the scope of thepresent invention. An equivalent structural or equivalent processalternation made by using the content of the specification and drawingsof the present invention, or an application of the content of thespecification and drawings directly or indirectly to another relatedtechnical field, shall fall within the protection scope of the presentinvention.

What is claimed is:
 1. A method for sending a preamble sequence, themethod comprising: determining a transmit power for sending a preamblesequence, wherein the transmit power meets the following formula:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}, wherein Power is the determinedtransmit power, Pmax is a maximum transmit power of user equipment, PLis obtained by estimating according to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, whereinPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep, andpreambleInitialReceivedTargetPower is an initial target receive power ofthe preamble sequence, DELTA_PREAMBLE is a power offset based on aformat of the preamble sequence, powerRampingStep is a power ramp step,preamble_transmission_counter is a retransmission count of the preamblesequence, and X_(i) is a power offset corresponding to a preamblesequence resource pool i for coverage enhancement random access; andsending the preamble sequence according to the determined transmitpower.
 2. The method according to claim 1, wherein the power offsetX_(i) meets PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ, wherein Δ≧0, and Δ is aconstant and a preset threshold.
 3. The method according to claim 2,further comprising: determining the power offset X_(i), whereindetermining the power offset X_(i) comprises: searching for the poweroffset X_(i) in ascending order of power offsets, or searching for thepower offset X_(i) in ascending order of repetition counts fortransmitting the preamble sequence.
 4. The method according to claim 2,wherein sending the preamble sequence comprises: transmitting thepreamble sequence by using a repetition count corresponding to thepreamble sequence resource pool i for coverage enhancement randomaccess.
 5. The method according to claim 2, wherein the determinedtransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL.
 6. The method according to claim 2,wherein the power offset X_(i) is a coverage enhancement amount that iscorresponding to the repetition count corresponding to the preamblesequence resource pool i for coverage enhancement random access.
 7. Themethod according to claim 2, wherein determining a transmit power forsending a preamble sequence comprises: obtainingPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) by performing calculation according to the power offsetX_(i), and sending the preamble sequence according toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter), to perform the preamble_transmission_counter^(th) randomaccess; if the preamble_transmission_counter^(th) random access fails,increasing preamble_transmission_counter by one, keeping X_(i)unchanged, and calculating the following again:RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter); and if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is met,performing transmission by using the repetition count corresponding tothe preamble sequence resource pool i for coverage enhancement randomaccess, wherein the transmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL; or if a conditionthat PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission)^(_) ^(counter)+PL−Pmax≦Δ is not met, searching for the power offsetX_(i) in ascending order of repetition counts or the power offsetsX_(i), and determining whether the found power offset X_(i) meetsPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ; and if a minimum value of X_(i) that meets theforegoing formula is found, performing transmission by using therepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access, wherein the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if the foregoing inequality cannot be met after allX_(i) are traversed, performing transmission by using a repetition countcorresponding to a preamble sequence resource pool i for coverageenhancement random access that is found at last, wherein the transmitpower is Pmax.
 8. The method according to claim 1, wherein informationabout the preamble sequence resource pool i for coverage enhancementrandom access is obtained from system information or is preset.
 9. Themethod according to claim 8, wherein the information about the preamblesequence resource pool i for coverage enhancement random accesscomprises at least one type of the following information: the repetitioncount corresponding to the preamble sequence resource pool i forcoverage enhancement random access and a coverage enhancement amountcorresponding to the preamble sequence resource pool i for coverageenhancement random access.
 10. User equipment, comprising: a processorconfigured to execute the following operation by invoking an operationinstruction: determining a transmit power for sending a preamblesequence, wherein the transmit power meets the following formula:Power=min{Pmax,PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL}, wherein Power is the determinedtransmit power, Pmax is a maximum transmit power of the user equipment,PL is obtained by estimating according to a downlink path loss, andPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter) is a target receive power of the preamble sequence, whereinPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)=preambleInitialReceivedTargetPower+DELTA_PREAMBLE−X_(i)+(preamble_transmission_counter−1)*powerRampingStep, andpreambleInitialReceivedTargetPower is an initial target receive power ofthe preamble sequence, DELTA_PREAMBLE is a power offset based on aformat of the preamble sequence, powerRampingStep is a power ramp step,power_transmission_counter is a repetition count for transmitting thepreamble sequence, and X_(i) is a power offset corresponding to apreamble sequence resource pool i for coverage enhancement randomaccess; and a sender configured to send the preamble sequence accordingto the determined transmit power.
 11. The user equipment according toclaim 10, wherein the power offset X_(i) meets:PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL−Pmax≦Δ, wherein Δ≧0, and Δ is a constant and a presetthreshold.
 12. The user equipment according to claim 11, wherein theprocessor is further configured to: search for the power offset X_(i) inascending order of power offsets; or search for the power offset X_(i)in ascending order of repetition counts for transmitting the preamblesequence.
 13. The user equipment according to claim 11, wherein thesender is further configured to transmit the preamble sequence by usinga repetition count corresponding to the preamble sequence resource pooli for coverage enhancement random access.
 14. The user equipmentaccording to claim 11, wherein the determined transmit power is:PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL.
 15. The user equipment according to claim 11, wherein thepower offset X_(i) is a coverage enhancement amount that iscorresponding to the repetition count corresponding to the preamblesequence resource pool i for coverage enhancement random access.
 16. Theuser equipment according to claim 11, wherein processor is configuredto: obtain PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter) by performing calculation according tothe power offset X_(i), and send the preamble sequence according toPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter), to perform the preamble_transmission_counter^(th) randomaccess; if the preamble_transmission_counter^(th) random access fails,increase preamble_transmission_counter by one, keep X_(i) unchanged, andcalculate the following again: PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter); and if a conditionthat PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission)^(_) ^(counter)+PL−Pmax≦Δ is met, perform transmission by using therepetition count corresponding to the preamble sequence resource pool ifor coverage enhancement random access, wherein the transmit power isPREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_) ^(transmission) ^(_)^(counter)+PL; or if a condition that PREAMBLE_RECEIVED_TARGET_POWER_(i)^(preamble) ^(_) ^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ is not met,search for the power offset X_(i) in ascending order of repetitioncounts or the power offsets X_(i) and determine whether the found poweroffset X_(i) meets PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL−Pmax≦Δ; and if a minimum value ofX_(i) that meets the foregoing formula is found, perform transmission byusing the repetition count corresponding to the preamble sequenceresource pool i for coverage enhancement random access, wherein thetransmit power is PREAMBLE_RECEIVED_TARGET_POWER_(i) ^(preamble) ^(_)^(transmission) ^(_) ^(counter)+PL; or if the foregoing inequalitycannot be met after all X_(i) are traversed, perform transmission byusing a repetition count corresponding to a preamble sequence resourcepool i for coverage enhancement random access that is found at last,wherein the transmit power is Pmax.
 17. The user equipment according toclaim 10, wherein information about the preamble sequence resource pooli for coverage enhancement random access is obtained from systeminformation or is preset.
 18. The user equipment according to claim 17,wherein the information about the preamble sequence resource pool i forcoverage enhancement random access comprises at least one type of thefollowing information: the repetition count corresponding to thepreamble sequence resource pool i for coverage enhancement random accessand a coverage enhancement amount corresponding to the preamble sequenceresource pool i for coverage enhancement random access.